"What's that? Oh, you want an answer to the life question. Well, nobody knows for sure—remember only about a quarter of the galaxy has been properly surveyed. But there are more than five million intelligent species known to the Empire. Do the math and you'll realize there have to be a fair number of species we've yet to meet."

―Crix Q5 Baobab, teaching at the Baobab Merchant Marine Academy's first day of orientation[src]

The galactic disk came to have three vertical layers: one in the middle that was 2,000 light years thick called the "thin slice" sandwiched between two 3,500 light year sections on either side of that called the "thick slice." The majority of the galaxy's approximately four hundred billion stars fell within the thin slice, though the thick slice had some, and there was also a great sphere around the galactic disk called the "stellar halo" that consisted of billions of stars with highly elliptical orbits.[9] Many of the stars ended up developing planets that orbited them over the succeeding eons.[10] Half of these star systems[8]—primarily within the thin slice[9]—maintained conditions favorable to life, ten percent of this half actually developed life, and only one in a thousand of the life-bearing worlds went on to bear true sentience.[8] Life would still be emerging on planets in the galaxy by 5,000,000,000 BBY.[11] Many of these forms of sentience would try to explain their conditions, forming religions. A number developed creation myths, detailing how their existence came to be,[12][13][14][15] whether that meant the creation of the galaxy,[15] the formation of their world,[14] or the origin of life.[16] The Mandalorian religion had a creation tale called the Akaanati'kar'oya, "The War of Life and Death" in Basic, and it posited that the stars in the sky were ancient Mandalorian leaders that had died.[15] Life that grew on worlds separated by great distances, primarily twenty million sentient species,[8] would go on to interact and integrate, experiencing and eventually recordinggalactic history.[1]

By the reign of the Galactic Empire, which began in 19 BBY, much would be known about the physical properties of the galaxy, from its stars to its planets, but only about a quarter of all stars in the galaxy were surveyed. Contemporary estimates stated that of all the stars, 7.1 billion were not dangerous to life while 3.2 billion of those supported actual star systems—it was proposed that at least one billion of them were inhabited to some degree, and Imperial census data showed 69 million that were populated significantly. There were 1.75 million planets considered by the Empire to be advanced and populous enough for full member status. Imperial records further showed five million cataloged examples of sentient species, but it was accepted plainly that there were many more undiscovered species in the galaxy.[9]

↑The New Essential Chronology states that the Ruusan Reformation occurred in 1000 BBY, which is the zero point of the calendar based on the Ruusan Reformation, so the difference between the calendar based on the Battle of Yavin and the Ruusan Reformation's year-notation system is 1,000 years. This date is derived using simple math based upon other confirmed dates.

↑The Essential Atlas places the Battle of Yavin, the zero point in the Galactic Standard Calendar, in 35:3 under the Great ReSynchronization dating system. The Essential Atlas also places the Battle of Selaggis on 43:2:28 and the Battle of Dathomir on 43:3:21. The Essential Guide to Warfare and The Essential Atlas both place the Battle of Dathomir in 8 ABY. The Essential Guide to Warfare also places the Battle of Selaggis in 7 ABY, confirming the placement of the division between each Galactic Standard Calendar year as the third month in the Great ReSynchronization year. Thus, there is a two-month gap between the two dating systems, and the first two months of a GrS year are the last two of the preceding Galactic Standard Calendar year. The Great ReSynchronization was instituted in 35 BBY, so there is a total difference of 35 years and 2 months between the two systems. This article's date is therefore derived from simple math based on this reference explanation.